Fleet
Rancher v2.5 introduced Fleet, a new way to deploy applications across clusters.
Fleet is GitOps at scale. For more information, refer to the Fleet section.
Multi-cluster Apps
In Rancher before v2.5, the multi-cluster apps feature was used to deploy applications across clusters. The multi-cluster apps feature is deprecated, but still available in Rancher v2.5.
Refer to the documentation here.